Industrial characteristics of precision casting
The most commonly used in precision casting is investme […]
The most commonly used in precision casting is investment casting, also known as lost wax casting: using a suitable investment material (such as paraffin) to make a melting mold; repeating the refractory coating and blasting sand on the investment mold, the hardened shell and Drying; then melting the internal melting mold to obtain a cavity; calcining the shell to obtain sufficient strength, burning off the residual investment material, pouring the required metal material; solidifying and cooling, and then sanding after shelling, thereby Get high precision finished products. Heat treatment and cold working and surface treatment according to product requirements. For example, sand casting, mass production of factories should create conditions using technologically advanced modeling and core making methods. The productivity of the old-fashioned shock-type or shock-pressure molding machine production line is not high enough. The labor intensity of the workers is large, the noise is large, and it is not suitable for the requirements of mass production. It should be gradually modified. For small castings, it is possible to use a horizontal or vertical type of boxes high-pressure molding machine production line, real modeling and high production efficiency, and a small footprint; for the middle part, various high-pressure molding machine production lines and gas can be selected. The molding line is designed to meet the requirements of fast and high-precision molding production lines. The core-making method can be used: high-speed core making methods such as cold core box, hot core box and shell core.
Medium-sized large castings can be considered for the application of resin self-hardening sand molding and core making.
Manual casting is still an important method for heavy-duty castings produced in small batches. The manual molding can be adapted to various complex requirements and is not flexible. It does not require many process equipment. Water glass sand type, VRH water glass sand type, organic ester water glass self-hardening sand type, clay dry type, resin self-hardening sand type and cement sand type can be applied; for heavy-duty castings produced by one piece, the pit modeling method is low in cost and put into production fast. The multi-box shape and the box-boxing method are suitable for mass production or long-term production of styling products. Although molds, sand boxes, etc. start to invest high, they can be compensated for saving mold time and improving product quality.
Casting methods such as low pressure casting, die casting, and centrifugal casting are only suitable for mass production because of the high cost of equipment and molds.
Conditional method should be suitable
For example, it is also the production of castings such as large machine bed, generally using the core forming method, not making the pattern and the sand box, and assembling the core in the pit; while the other factory adopts the sand box modeling method to make the appearance. Different enterprise production conditions (including equipment, site, staff quality, etc.), production habits, and accumulated experience are different. It should be considered according to these conditions what products are suitable and what products are not suitable (or not).
Precision requirements and costs
The castings obtained by various casting methods have different precisions, initial investment and productivity are also inconsistent, and the final economic benefits are also different. Therefore, to be more, faster, better, and more economical, we should take into account all aspects. A preliminary cost estimate should be made for the casting method chosen to determine the casting method that is economically efficient and that guarantees the casting requirements.
Although the development of China's foundry industry is in a relatively difficult period, from a long-term perspective, China's precision casting industry still has certain hopes for development, market demand has slowly begun to pick up, and coupled with China's foundry industry. The strength of the development has a strong strength, I believe that China's foundry industry will certainly achieve gratifying results.
Experts said that in order to fundamentally improve the level of casting technology, the following four points must be achieved: First, develop simulation technology, improve the accuracy of prediction, strengthen process control, and improve yield. The problem of regularity is not well mastered, which affects the yield in mass production. Second, the combination of production, study and research. In addition to the enhancement of innovation consciousness and the improvement of research and development capabilities, the independent innovation of enterprises also needs to attach importance to and strengthen the combination of “production, learning and research” with precision casting enterprises as the main body. Third, attach importance to material research and development. Materials are the foundation of industry, and there is still a lot of work to do. In the aerospace field, research and smelting technologies for some new materials such as alloy materials, especially high-temperature alloys, have yet to be improved, and the gap with foreign countries is still large. Fourth, pay attention to the improvement of equipment technology. The process is mainly the problem of equipment. Many key equipments, such as some directional solidification equipment, mainly rely on imports, so the research and development of precision casting equipment is still the focus.